Method for transmitting channel quality information based on differential scheme

Abstract

A method for transmitting channel quality information based on a differential scheme is disclosed. When channel quality information of a predetermined number of sub-bands selected by a receiver in a frequency selective channel is transmitted, total average channel information is transmitted. Channel information of the selected sub-bands is transmitted as sub-band differential information associated with average channel information. In this case, the sub-band differential information may be denoted by a specific value contained in a differential-value range including only positive (+) values. If at least two channel quality information is transmitted by a MIMO system, channel quality information of one channel is transmitted, then channel quality information of the other channel is transmitted as spatial differential information. In this case, the spatial differential information is denoted by a specific value contained in a differential-value range asymmetrical on the basis of “0”.

1. A method for transmitting channel quality information (CQI) in a mobile communication system, the method comprising:
 calculating a first CQI value for a first set of sub-bands; 
 selecting a second set of sub-bands which are a preferred subset of the first set of sub-bands; 
 determining a differential CQI value among predetermined number of differential CQI values based on an offset value given by: 
 the offset value=a second CQI value for the second set of sub-bands−the first CQI value, 
 wherein the predetermined number of differential CQI values are allocated more on a first case in which the offset value has a positive value than a second case in which the offset value has a negative value; and 
 transmitting, to the base station, the differential CQI value determined among the predetermined number of differential CQI values. 
 
     
     
       2. The method according to  claim 1 , wherein the second set of sub-bands have the highest CQI values amongst the first set of sub-bands. 
     
     
       3. The method according to  claim 1 , wherein each of the sub-bands in the second set of sub-bands has a relatively high CQI value compared to all of the sub-bands in the first set of sub-bands. 
     
     
       4. The method according to  claim 1 , wherein the first set of sub-bands includes all of the sub-bands in a given frequency range. 
     
     
       5. The method according to  claim 4 , wherein the mobile communication system comprises:
 a plurality of user terminals, base stations, and network entities, and wherein the given frequency range is determined by a network entity. 
 
     
     
       6. The method according to  claim 1 , wherein the differential CQI value is represented as a 2-bit value, and
 wherein transmitting the differential CQI value comprises: 
 transmitting the 2-bit value representing the differential CQI value. 
 
     
     
       7. The method according to  claim 6 , wherein transmitting the 2-bit value representing the differential CQI value comprises:
 transmitting the 2-bit value representing the differential CQI in a Physical Uplink Shared Channel (PUSCH). 
 
     
     
       8. The method according to  claim 1 , wherein the differential CQI value is within a predetermined range of positive integer values. 
     
     
       9. A user equipment for transmitting channel quality information (CQI) to a base station in a mobile communication system, the user equipment comprising:
 a receiver configured to receive signals from the base station; 
 a processor configured to calculate a first CQI value for a first set of sub-bands, to select a second set of sub-bands which are a preferred subset of the first set of sub-bands, to determine a differential CQI value among predetermined number of differential CQI values based on an offset value given by: 
 the offset value=a second CQI value for the second set of sub-bands−the first CQI value, 
 wherein the predetermined number of differential CQI values are allocated more on a first case in which the offset value has a positive value than a second case in which the offset value has a negative value; and 
 a transmitter configured to transmit the differential CQI value determined among the predetermined number of differential CQI values to the base station. 
 
     
     
       10. The user equipment according to  claim 9 , wherein the second set of sub-bands have the highest CQI values amongst the first set of sub-bands. 
     
     
       11. The user equipment according to  claim 9 , wherein each of the sub-bands in the second set of sub-bands has a relatively high CQI value compared to all of the sub-bands in the first set of sub-bands. 
     
     
       12. The user equipment according to  claim 9 , wherein the first set of sub-bands includes all of the sub-bands in a given frequency range. 
     
     
       13. The user equipment according to  claim 9 , wherein the differential CQI value is represented as a 2-bit value, and
 wherein the transmitter transmits the 2-bit value representing the differential CQI value to the base station. 
 
     
     
       14. The user equipment according to  claim 13 , wherein the transmitter transmits the 2-bit value representing the differential CQI value in a Physical Uplink Shared Channel (PUSCH). 
     
     
       15. The user equipment according to  claim 9 , wherein the differential CQI value is within a predetermined range of positive integer values.